This invention relates to a continuously variable transmission for a motor vehicle having a plurality of clutches and brakes designed as wet disk sets.
Continuously variable transmissions for motor vehicles are widely known. EP B 434 525 thus describes an automatic transmission for motor vehicles which has planetary gear sets shifted by means of clutches and brakes and connected with a hydraulic torque converter provided with a lock-up clutch. This automatic transmission has one input shaft and one output shaft with a double planetary gear set, at least one power path between the input shaft and the double planetary gear set, the same as three clutches and two brakes the selective engagement of which arranged in pairs determines different reduction ratios between the input shaft and the output shaft. Six forward gears and one reverse gear can be obtained by the three clutches and two brakes.
In a multiplicity of continuously variable transmissions at least the clutches are designed as wet multi-disk clutches cooled by an oil flow. The oil is mostly passed from inside to outside by the disk set, the inner disk carrier rotating during the operation in order to press the oil in radial direction through the disk set. If this is not the case, the disk set is no longer cooled over the whole lining surface.
In many transmissions there is an operating state, namely, the xe2x80x9cstationary disengagementxe2x80x9d, in which the outer disk carrier rotates with its disk set while the inner disk carrier remains fixed with its disk set. The cold oil centrally supplied, via the hollow shaft, therefore, is not splashed from the inside to the outside through the disk set so that an insufficient cooling results.
The problem on which this invention is based is to configure a continuously variable transmission with wet multi-disk clutches so that even in the operating state of stationary disengagement with fixed inner disk carrier and rotating outer disk carrier the disk set is sufficiently cooled.
It is proposed, according to the invention, that with the clutch having in the operating state of stationary disengagement the fixed inner disk carrier and the rotating outer disk carrier, a splash-lubrication pot is associated which is situated in the space surrounded by the inner disk carrier coaxially to the hollow shaft through which the cold oil of the clutch is fed and that the splash-lubrication pot is connected with a continuously rotating part of the clutch. The outer wall of the splash-lubrication pot is provided with holes which allow a radial exit of the oil absorbed in direction of the disk set. The rotating part which is lubricated by the splash-lubrication pot is located conveniently to the appertaining clutch baffle plate.
The cold oil exiting through the hollow shaft is, therefore, absorbed with the splash-lubrication pot, the collected oil being formed by rotation into a rotating oil column whereby a rotation pressure forms on the inner side of the outer wall of the splash-lubrication pot by the holes provided in the outer wall of the splash-lubrication pot, the oil is the sprayed from the inside against the disk set so that the latter can now be effectively cooler.